Zendesk Error: 403 Forbidden

The Zendesk credentials that you have used may not have the proper permissions to perform integrations. (ie. no read/write access)

Solution:

To check if your account has the valid credentials, log in to your zendesk account, and click on view profile on the top right hand corner of your zendesk interface. after which look for your role as seen below, and make sure you have administrator access.